From Fig. REF  we can also see that the difference between \(\Omega ^2\)  and \( \Omega ^2_\mathrm {eff}\)  lies mainly in the region near the bounce. However, as the curvature term \(a^{\prime \prime }/a\)  overwhelmingly dominates in this region, it is usually expected that the impact of the different choices of \(\Omega ^2\)  on the power spectrum might not be very large [1]}, [2]}, [3]}. However,
in [4]}, it was found that the relative difference in the magnitude of the power spectrum in the IR and oscillating regimes could be as large as \(10\%\) , where the relative difference is defined
as,
\({\cal {E}} \equiv 2\left|\frac{{\cal {P}}_1 - {\cal {P}}_2}{{\cal {P}}_1 + {\cal {P}}_2}\right|.\) 
